Papers by Claude Saegerman
The Veterinary Journal, 2012
The aim of this study was to determine whether a single dose of an inactivated bluetongue virus s... more The aim of this study was to determine whether a single dose of an inactivated bluetongue virus serotype 8 (BTV-8) vaccine altered semen quality in rams. Twenty sexually mature rams were assigned to three experimental groups: two groups of four animals were vaccinated and a third group of four animals was unvaccinated. The first group included rams with a history of natural BTV-8 infection in 2007 and the second and third groups included BTV-8 naïve rams. Semen was collected prior to vaccination and for 4 months post-vaccination. There were no significant differences in semen quality traits, including motility and concentration of spermatozoa, and percentages of living, normal dead and abnormal dead spermatozoa, between vaccinated and unvaccinated groups, or over time (P>0.05). The BTV-8 vaccine tested in this study did not appear to have any adverse effect on semen quality in rams.
Emerging Infectious Diseases, 2012
To prioritize 100 animal diseases and zoonoses in Europe, we used a multicriteria decision-making... more To prioritize 100 animal diseases and zoonoses in Europe, we used a multicriteria decision-making procedure based on opinions of experts and evidence-based data. Forty international experts performed intracategory and intercategory weighting of 57 prioritization criteria. Two methods (deterministic with mean of each weight and probabilistic with distribution functions of weights by using Monte Carlo simulation) were used to calculate a score for each disease. Consecutive ranking was established. Few differences were observed between each method. Compared with previous prioritization methods, our procedure is evidence based, includes a range of fields and criteria while considering uncertainty, and will be useful for analyzing diseases that affect public health.
Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment, 2012
Young, old, pregnant and immuno-compromised persons are of great concern for risk assessors as th... more Young, old, pregnant and immuno-compromised persons are of great concern for risk assessors as they represent the sub-populations most at risk. The present paper focuses on risk assessment linked to furan exposure in children. Only the Belgian population was considered because individual contamination and consumption data that are required for accurate risk assessment were available for Belgian children only. Two risk assessment approaches, the so-called deterministic and probabilistic, were applied and the results were compared for the estimation of daily intake. A significant difference between the average Estimated Daily Intake (EDI) was underlined between the deterministic (419 ng kg⁻¹ body weight (bw) day⁻¹) and the probabilistic (583 ng kg⁻¹ bw day⁻¹) approaches, which results from the mathematical treatment of the null consumption and contamination data. The risk was characterised by two ways: (1) the classical approach by comparison of the EDI to a reference dose (RfD(chroni...
Food products should not contain unsafe levels of chemical contaminants. However, it is not possi... more Food products should not contain unsafe levels of chemical contaminants. However, it is not possible to monitor each and every one of the many thousands of chemicals that are used in our advanced societies. Chemical contaminants in foodstuffs of animal origin may be classified into three categories: natural contaminants (e.g. mycotoxins), environmental contaminants linked to industrialisation and/or urbanisation (e.g. dioxins and dioxin-like compounds) and authorised chemical products (e.g. residues of veterinary medical products). Chemical hazards may contaminate foodstuffs of animal origin all the way from farm to fork. Contamination may occur in any of the different production systems, and it is difficult to make comparisons between production systems (e.g. extensive versus intensive farming systems) with regard to food safety. Even when we take into account the latest analytical methods, which can detect ever-smaller quantities of residues, the relative importance of chemical contaminants seems to have declined during recent decades due to improvements in information and prevention. Nonetheless, individual incidents can never be ruled out and may have serious economic, health or social repercussions. Particular attention must be paid to chemical hazards, in order to reduce as much as possible the risks to livestock and to the consumer. Continued monitoring and periodic reassessment of risks posed by these contaminants (at the national level) are needed to detect or anticipate new problems, so that appropriate actions can be taken in the interest of public health. More attention should be paid to the production of detailed information, especially with regard to background data (e.g. the objectives of the monitoring, sampling methods, chemicals to be analysed, analytical methods, detection limits, raw data and specified units), in order to obtain a better basis for risk assessment. Such risk assessment provides control authorities with an effective tool for the exchange of information and measures to be taken to ensure food safety.
RESUME : L'utilisation d'arbres de régression et de classification constitue un outil pré... more RESUME : L'utilisation d'arbres de régression et de classification constitue un outil précieux d'aide à la décision clinique pour des maladies à prévalence faible ainsi que pour des maladies dont il n'existe pas encore de test de diagnostic de laboratoire (maladies émergentes). Ces arbres permettent de classer des observations cliniques et autres sur la base d'un ensemble de variables prédictives,
Veterinary microbiology, Jan 20, 2004
Three i-ELISAs using LPS, the immunodominant component of Brucella abortus, were developed with t... more Three i-ELISAs using LPS, the immunodominant component of Brucella abortus, were developed with three different conjugates: monoclonal antibodies 1C8 (anti-bovine IgG(1)) and 3H3 (mainly specific for bovine IgG(2) but also reacting with IgG(1)) and protein G (reacts with both bovine IgG subclasses). Using a cut-off value of 2.5U/ml, the i-ELISA with 3H3 as conjugate had a specificity (95% CI: 98.32-99.63%) that was significantly higher than the same assay with 1C8 (95% CI: 96.08-98.26%) or PG (95% CI: 95.83-98.09%). In areas where false positive serological reactions (FPSR) were common, the specificity of the i-ELISAs decreased significantly. The specificity of the i-ELISAs increased with the age of the animals tested, irrespective of the conjugate. The specificity of the i-ELISAs and traditional tests was also examined using sera from animals infected per os with bacteria bearing LPS similar to the Brucella LPS. It appeared that Yersinia enterocolitica O:9, Xanthomonas maltophilia ...
The Veterinary record, Jan 21, 1999
Brucellergene OCB (Rhône-Mérieux) was used as an allergen to define the intrinsic parameters of a... more Brucellergene OCB (Rhône-Mérieux) was used as an allergen to define the intrinsic parameters of a skin test and to compare its properties with serology for the diagnosis of bovine brucellosis. The skin test was also evaluated for its capacity to solve problems associated with false positive reactions in serological tests. The optimal reading delay for the skin test was 72 hours. The brucellosis allergic reaction was two to three times less intense than the tuberculosis allergic reaction. An increase of 1.1 mm or more in the skin thickness was therefore considered to be an adequate cut-off. The specificity calculated for 1192 brucellosis-free animals (including animals from brucellosis-free herds in which false positive serological reactions had been reported) was 99-83 per cent (95 per cent confidence interval [CI] 99-40 to 99-98 per cent). The sensitivity determined from 27 experimentally infected heifers ranged from 93 per cent (95 per cent CI 76 to 100 per cent) to 78 per cent (9...
The Veterinary record, Jan 24, 2008
PLOS ONE, 2015
A large-scale study on canine Leishmania infection (CanL) was conducted in six localities along a... more A large-scale study on canine Leishmania infection (CanL) was conducted in six localities along a west-east transect in the Algerian littoral zone (Tlemcen, Mostaganem, Tipaza, Boumerdes, Bejaia, Jijel) and covering two sampling periods. In total 2,184 dogs were tested with an indirect fluorescent antibody test (IFAT) and a direct agglutination test (DAT). Combined multiple-testing and several statistical methods were compared to estimate the CanL true prevalence and tests characteristics (sensitivity and specificity). The Bayesian full model showed the best fit and yielded prevalence estimates between 11% (Mostaganem, first period) and 38% (Bejaia, second period). Sensitivity of IFAT varied (in function of locality) between 86% and 88% while its specificity varied between 65% and 87%. DAT was less sensitive than IFAT but showed a higher specificity (between 80% and 95% in function of locality or/and season). A general increasing trend of the CanL prevalence was noted from west to east. A concordance between the present results and the incidence of human cases of visceral leishmaniasis was observed, where also a maximum was recorded for Bejaia. The results of the present study highlight the dangers when using IFAT as a gold standard.
Veterinary Parasitology, 2008
Echinococcus multilocularis causes a rare but potentially lethal zoonotic infection in humans. Th... more Echinococcus multilocularis causes a rare but potentially lethal zoonotic infection in humans. This tapeworm is known to be endemic in foxes in several countries of Western and Central Europe. In Western Europe, the common vole (Microtus arvalis) and the water vole (Arvicola terrestris) are considered to be the most important intermediate host species of this cestode whereas the red fox is by far the most important final host. The purpose of this study was to provide data on the prevalences in Wallonia (Southern part of Belgium) both in the red fox and in different potential intermediate hosts.
Journal of Clinical Microbiology, 2006
A major limitation is the lack of sufficiently informative or epidemiologically well evaluated mo... more A major limitation is the lack of sufficiently informative or epidemiologically well evaluated molecular methods for typing. Here, we report an evaluation of a high-throughput method based on 29 mycobacterial interspersed repetitive unit-variable-number tandem-repeat MIRU-VNTR) loci to genotype 127 M. bovis isolates from cattle from 77 different Belgian farms, representative of a nationwide collection obtained from 1995 to 2003. MIRU-VNTR stability was demonstrated by analyzing a series of 74 isolates in total, obtained from different animals from a single farm or from different farms with an identified epidemiological link. The genotyping results and the genotypic diversity (h) were compared with those obtained by IS6110 restriction fragment length polymorphism (RFLP) analysis and spoligotyping. Among 68 isolates with no known epidemiological link, MIRU-VNTR typing discriminated better than either RFLP analysis or spoligotyping, with isolates taken individually (32 versus 16 and 17 genotypes; h ؍ 0.91 versus 0.73 and 0.85, respectively) or in combination (32 versus 28 genotypes; h ؍ 0.91 versus 0.92). Maximal resolution was already achieved with a subset of 9 loci. The observed congruence of the genetic relationships based on IS6110 RFLP analysis, spoligotyping, and MIRU-VNTR markers is consistent with a clonal population structure of M. bovis. These results support MIRU-VNTR typing as a convenient and discriminatory technique for analysis of the population structure of M. bovis in much greater detail and for addressing some still unresolved issues in the epidemiology of the pathogen.
Le taux de prévalence apparente moyenne de l'encéphalopathie spongiforme bovine en Belgique en 20... more Le taux de prévalence apparente moyenne de l'encéphalopathie spongiforme bovine en Belgique en 2002Belgique en et 2003 . Depuis 2001, le système de dépistage de cette zoonose repose principalement sur l'utilisation d'un test « rapide ». Le seul test rapide utilisé en Belgique à cette époque était le test Platelia ® commercialisé par la firme Bio-Rad. Lors de la mise au point de ce test, sa sensibilité et sa spécificité ont été estimées respectivement à 100% [intervalle de confiance 95 % (IC 95 %) : 99 -100%] et 100% [IC 95 % : 99,7 -100%]. Pour ce faire, la sensibilité a été définie comme la capacité du test à identifier correctement un animal cliniquement atteint d'ESB, et la spécificité comme la capacité à identifier correctement un animal non-infecté. Ce test a pourtant été utilisé à grande échelle comme moyen de dépistage au sein d'une population d'animaux ne présentant pas de manifestations cliniques d'ESB. Dans ces conditions, la sensibilité et la spécificité du test pourraient donc s'éloigner des valeurs initiales et la prévalence réelle de l'ESB pourrait diverger de la prévalence apparente. Les sensibilité et spécificité du test rapide utilisé, ainsi que la prévalence réelle de l'ESB en Belgique ont été estimées par méthode bayésienne pour les années 2002 et 2003. Les données a priori ont été obtenues par avis d'experts et la vraisemblance a été déterminée grâce aux données concernant les animaux testés. Une distribution a posteriori de la prévalence de l'ESB a été déterminée par des méthodes Markov Chain Monte Carlo avec échantillonneur de Gibbs. Le taux de prévalence réelle de l'ESB en Belgique en 2002 et 2003 se situe dans un intervalle de crédibilité (IC) allant d'un ordre de grandeur de 10 -7 à 10 -5 . Les spécificité et sensibilité du test rapide ont été estimées respectivement à 99,99% [IC : 99,99 -100 %] et 91,23% [IC : 81,69 -91,64 %]. Cette étude montre l'importance d'une analyse critique de la sensibilité et de la spécificité des tests de diagnostic de l'ESB et de la prévalence apparente de cette zoonose, vu leurs conséquences importantes pour l'épidémiosurveillance active et passive. Mots clés : Encéphalopathie spongiforme bovine, test rapide, modélisation bayésienne, prévalence réelle, sensibilité, spécificité. ________________________ * Texte de la conférence présentée à la Journée AEEMA, 20 mai 2005 infectieuses et parasitaires,
Veterinary Microbiology, 2009
Preventive Veterinary Medicine, 2004
Our objective was to determine the seroprevalence of Hypoderma spp. and to develop a spatial mode... more Our objective was to determine the seroprevalence of Hypoderma spp. and to develop a spatial model describing the risk surface of warble-fly infection in Belgian cattle herds (adjusting for herd size, herd type, local temperature, rainfall, relative air humidity and land-cover).This survey was carried out in 390 selected herds of all types (dairy, mixed and beef) from December 1997 to
Veterinary Microbiology, 2002
Collaborative work was financed by the EU to develop and assess new diagnostic tools that can dif... more Collaborative work was financed by the EU to develop and assess new diagnostic tools that can differentiate between bovine brucellosis and bovine infections due to Yersinia enterocolitica O:9 either in conjunction with, or as an alternative to, the classical serological, bacteriological or allergic skin tests. Sixteen heifers were experimentally infected with Brucella abortus biovar 1 (five heifers), Brucella suis biovar 2 (two heifers), Y. enterocolitica O:9 (six heifers) and Y. enterocolitica O:3 (three heifers). Four heifers, naturally infected with Y. enterocolitica O:9 that presented aspecific brucellosis serological reactions were also included in the experiment. A self-limited infection was induced in cattle by B. suis biovar 2. All the brucellosis serological tests used, i.e. the slow agglutination test (SAW), the Rose Bengal test (RB), the complement fixation test (CFT), indirect and competitive ELISA's, lacked specificity when used to analyze sera from Y. enterocolitica O:9 infected animals. A Yersinia outer membrane proteins (YOPs)-ELISA was also used and although the test is able to detect a Yersinia group infection, it provided no evidence of whether or not there is a possible brucellosis infection when dual infections are present. The brucellergen IFN-gamma test showed a lack of specificity also. The only test that was proven to be specific is the brucellergen skin test. All brucellosis serological tests, except the indirect ELISA, were limited in their ability to detect B. abortus persistently infected animals. Based on these experimental studies, a strategy was implemented as part of the year 2001 Belgian Brucellosis Eradication Program to substantiate the eradication of bovine brucellosis. Epidemiological inquiries have identified risk factors associated with aspecific serological reactions, possible transmission and infection of cattle by B. suis biovar 2 from infected wild boars; and both legal and administrative measures taken by the veterinary services. No cases of bovine brucellosis have been confirmed in Belgium since March 2000.
A marketing authorisation for a veterinary vaccine is granted after the quality, safety and effic... more A marketing authorisation for a veterinary vaccine is granted after the quality, safety and efficacy of the product have been assessed in accordance with legal standards. The assessment includes complete characterisation and identification of seed material and ingredients, laboratory and host animal safety and efficacy studies, stability studies, and post-licensing monitoring of field performance. This assessment may not be possible during the emergence of a new animal disease, but several mechanisms exist to allow for the availability of products in an emergency animal health situation, e.g. autogenous biologics, conditional licences, experimental and emergency use authorisations, the importation of products in use elsewhere in the world and pre-approved vaccine banks. Using the emergence of bluetongue in northern Europe as an example, the regulatory issues regarding the temporary authorisation of animal vaccination are described. Several conditions must be fulfilled before a temporary authorisation can be granted, e.g. inactivated vaccines should be used in order to exclude reversion to virulence and reassortment between vaccine viruses and/or field strains of the bluetongue virus; decision-making must be supported by scientific evidence and risk analysis; there must be a complete census of the susceptible animals that were vaccinated; vaccination protocols must be adhered to and there must be a scheme allowing for registration, delivery and follow-up of vaccination, and monitoring, analysis and, possibly, adjustment of field use of the vaccination. This temporary authorisation must be replaced by a full authorisation as quickly as possible.
PloS one, 2009
Over the last two winters, there have been large-scale, unexplained losses of managed honey bee (... more Over the last two winters, there have been large-scale, unexplained losses of managed honey bee (Apis mellifera L.) colonies in the United States. In the absence of a known cause, this syndrome was named Colony Collapse Disorder (CCD) because the main trait was a rapid loss of adult worker bees. We initiated a descriptive epizootiological study in order to better characterize CCD and compare risk factor exposure between populations afflicted by and not afflicted by CCD. Of 61 quantified variables (including adult bee physiology, pathogen loads, and pesticide levels), no single measure emerged as a most-likely cause of CCD. Bees in CCD colonies had higher pathogen loads and were co-infected with a greater number of pathogens than control populations, suggesting either an increased exposure to pathogens or a reduced resistance of bees toward pathogens. Levels of the synthetic acaricide coumaphos (used by beekeepers to control the parasitic mite Varroa destructor) were higher in contro...
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Papers by Claude Saegerman